As aircraft weights and speeds have increased, the brake energy required to stop these aircraft has also increased. To account for these increases, modern aircraft include large and robust wheel brakes designed to be prepared for worst case conditions including an ability to apply the maximum brake pressure needed to bring the aircraft to the shortest possible stop after a high speed rejected take-off or accounting for a partial failure of one or more of the wheel brakes. While these wheel brakes are effective in worst case conditions, precise control of the wheel brakes while the aircraft is on the ground at low speeds (e.g., taxi and parking speeds) is difficult.
As one example, hydraulic wheel brake systems include a brake control valve for controlling the amount of pressure provided to the wheel brakes in response to a brake command provided by a pilot. Under normal deceleration conditions during landing of the aircraft, pressure control by the brake control valve is generally linear relative to the brake command provided by the pilot. In contrast, pressure control by the brake control valve is generally non-linear relative to the brake command provided by the pilot when the aircraft is at low speeds. In particular, because only a minimal amount of pressure is necessary to control the aircraft by the wheel brakes at low speeds, small changes in positioning of the brake control valve can result in large changes in the pressure provided to the wheel brakes. To this end, this generally non-linear relationship between the position of the brake control valve and the pressure provided to the wheel brakes can result in erratic braking of the aircraft by the pilot thereby diminishing passenger comfort within the aircraft.
Accordingly, it is desirable to provide an improved system for controlling a wheel brake. Furthermore, other desirable features and characteristics will become apparent from the subsequent summary and detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.